OK guys can you help? I have a bracket made out of 5mm mild steel. to get the same stiffness how thick would it need to be if I made it from aluminium?? Duh basic stuff probably but I'm not sure how to calculate, Thanks

Re: calculate aluminium thickness?? Remember that the bending a beam is a function of the moment of inertia of the beam. For a retangular beam I = H^3 * W Is the thickness change in the direction of the load or perpendicular to the load. If the thickness change is in the direction of the load the H(A) = (E(S)/E(A))^3 * H(S) Where H(A) or W(A)= the thickness of the Aluminum H(S) or W(S) = the thickness of the Steel E(A) = elastic modulus of the aluminum E(S) = elastic modulus of the steel If the thickness change is perpendicular to the load then the equation is W(A) = (E(S)/E(A)) * W(S)

Re: calculate aluminium thickness?? Moment of inertia of a rectangular beam is 1/12 x b x h^3 "h" is the direction in line with your load. Clearly, you get a lot more bang for your buck by increasing h, because you're cubing that number. Think of joists in your home, or I-beams.

Re: calculate aluminium thickness?? if u compare aluminium and steel result is aluminium having a high ductility but law compressive strength where as in steel this property are reverse manner so obvious that aluminium bracket required more thickness compared to steel, during bracket manufacturing some bending effect are occurred on face area of bracket Remember that the bending a beam is a function of the moment of inertia of the beam. For a retangular beam I = H^3 * W Is the thickness change in the direction of the load or perpendicular to the load. If the thickness change is in the direction of the load the H(A) = (E(S)/E(A))^3 * H(S) Where H(A) or W(A)= the thickness of the Aluminum H(S) or W(S) = the thickness of the Steel E(A) = elastic modulus of the aluminum E(S) = elastic modulus of the steel If the thickness change is perpendicular to the load then the equation is W(A) = (E(S)/E(A)) * W(S)

Re: calculate aluminium thickness?? You can also change the design of the bracket by including say a bird beak in the corner to stiffen up the bracket which will allow you to reduce the thickness of it when made from ally. Geoff

basically if you need a simple rule of thumb use a X2 factor btw mild steel thickness and Al regards, PS:" basically" rarely makes the optimum solution